1. Technical Field
The present disclosure relates to a printed circuit board.
2. Description of Related Art
Radio frequency current is known to exist at edges of multilayer high-speed printed circuit boards. The radio frequency current flows to low impedance sections, such as ground layers, thus electro-magnetic radiation is produced. This phenomenon is known as ‘fringing effect’. According to the 20 H rule, if the distance between a power layer and the ground layer is H, extending the edges of the ground layer by 20 H can reduce electro-magnetic radiation of the fringing effect by 70%. However, extending the edges of the ground layer by 20 H may be difficult when the distance H between the power layer and the ground layer is large.